Table 3.
Trend in seropositivity rate in SARS-CoV-2 naive cohort.
| Variable | Second sample,21 days post-V2 | Third sample,3-months post-V2 | Fourth sample,6-months post-V2 | P∗ |
|---|---|---|---|---|
| Overall seropositivity, n/N (%) | 342/360 (95.0) | 311/360 (86.4) | 259/360 (71.9) | <0.001 |
| Age | ||||
| ≤60 years, n/N (%) | 295/306 (96.4) | 271/306 (88.6) | 238/306 (77.8) | <0.001 |
| >60 years, n/N (%) | 47/54 (87) | 40/54 (74.1) | 21/54 (38.9) | <0.001 |
| P# value | 0.010 | 0.008 | 0.016 | |
| Sex | ||||
| Female, n/N (%) | 142/148 (95.9) | 130/148 (87.8) | 34/148 (23) | <0.001 |
| Male, n/N (%) | 200/212 (94.3) | 181/212 (85.4) | 55/212 (25.9) | <0.001 |
| P# value | 0.625 | 0.536 | 0.537 | |
| Body-mass index (BMI) | ||||
| BMI <25 kg/m2, n/N (%) | 245/257 (95.3) | 221/257 (86) | 60/257 (23.3) | <0.001 |
| BMI 25–29.9 kg/m2, n/N (%) | 59/63 (93.7) | 56/63 (88.9) | 17/63 (27) | <0.001 |
| BMI ≥30 kg/m2, n/N (%) | 38/40 (95) | 34/40 (85) | 12/40 (30) | <0.001 |
| P# value | 0.860 | 0.798 | 0.597 | |
| Co-morbidities | ||||
| Any Co-morbidities, n/N (%) | 78/84 (92.9) | 67/84 (79.8) | 29/84 (34.5) | <0.001 |
| No Co-morbidities, n/N (%) | 264/276 (95.7) | 244/276 (88.4) | 60/276 (21.7) | <0.001 |
| P# value | 0.389 | 0.048 | 0.021 | |
| Blood group | ||||
| A + ve, n/N (%) | 69/74 (93.2) | 67/74 (90.5) | 20/74 (27) | <0.001 |
| B + ve, n/N (%) | 96/100 (96) | 87/100 (87) | 26/100 (26) | <0.001 |
| AB + ve, n/N (%) | 17/19 (89.5) | 15/19 (78.9) | 7/19 (36.8) | <0.001 |
| O + ve, n/N (%) | 137/144 (95.1) | 122/144 (84.7) | 31/144 (21.5) | <0.001 |
| A-ve, n/N (%) | 6/6 (100) | 6/6 (100) | 1/6 (16.7) | <0.001 |
| B-ve, n/N (%) | 8/8 (100) | 6/8 (75) | 3/8 (37.5) | <0.001 |
| AB-ve, n/N (%) | 2/2 (100) | 2/2 (100) | 0/2 (0) | <0.001 |
| O-ve, n/N (%) | 7/7 (100) | 6/7 (85.7) | 1/7 (14.3) | <0.001 |
| P# value | 0.389 | 0. 197 | 0.080 | |
| Type 2 diabetes mellitus (T2DM) | ||||
| Yes, T2DM, n/N (%) | 31/37 (83.8) | 27/37 (73) | 16/37 (43.2) | <0.001 |
| No, T2DM, n/N (%) | 311/323 (96.3) | 284/323 (87.9) | 250/323 (77.4) | <0.001 |
| P# value | 0.006 | 0.017 | 0.007 | |
| Duration of T2DM | ||||
| Duration <5 years, n/N (%) | 6/6 (100) | 5/6 (83.3) | 2/6 (33.3) | <0.001 |
| Duration 5–10 years, n/N (%) | 16/21 (76.2) | 14/21 (66.7) | 10/21 (47.6) | <0.001 |
| Duration >10 years, n/N (%) | 9/10 (90) | 8/10 (80) | 4/10 (40) | <0.001 |
| P# value | 0.001 | 0.046 | 0.042 | |
| Hypertension (HTN) | ||||
| Yes, HTN, n/N (%) | 62/67 (92.5) | 52/67 (77.6) | 21/67 (31.3) | <0.001 |
| No, HTN, n/N (%) | 280/293 (95.6) | 259/293 (88.4) | 68/293 (23.2) | <0.001 |
| P# value | 0.348 | 0.029 | 0.208 | |
| Duration of HTN | ||||
| Duration <5 years, n/N (%) | 22/22 (100) | 18/22 (81.8) | 5/22 (22.7) | <0.001 |
| Duration 5–10 years, n/N (%) | 28/32 (87.5) | 24/32 (75) | 12/32 (37.5) | <0.001 |
| Duration >10 years, n/N (%) | 12/13 (92.3) | 10/13 (76.9) | 4/13 (30.8) | <0.001 |
| P# value | 0.148 | 0.116 | 0.325 | |
| Dyslipidaemia | ||||
| Yes, Dyslipidaemia, n/N (%) | 18/19 (94.7) | 15/19 (78.9) | 6/19 (31.6) | <0.001 |
| No, Dyslipidaemia, n/N (%) | 324/341 (95.0) | 296/341 (86.8) | 83/341 (24.4) | <0.001 |
| P# value | 0.973 | 0.579 | 0.662 | |
| Ischemic Heart Disease (IHD) | ||||
| Yes, IHD, n/N (%) | 8/8 (100) | 6/8 (75) | 3/8 (37.5) | <0.001 |
| No, IHD, n/N (%) | 334/352 (94.9) | 305/352 (86.6) | 86/352 (24.4) | <0.001 |
| P# value | 0.999 | 0.299 | 0.414 | |
| Vaccine type | ||||
| Covishield, n/N (%) | 295/299 (98.7) | 277/299 (92.6) | 66/299 (22.1) | <0.001 |
| Covaxin, n/N (%) | 47/61 (77) | 34/61 (55.7) | 23/61 (37.7) | <0.001 |
| P# value | <0.001 | <0.001 | 0.009 | |
| Vaccine type (Propensity matched) | ||||
| Covishield, n/N (%) | 39/41 (95.12) | 37/41 (90.24) | 11/41 (26.82) | <0.001 |
| Covaxin, n/N (%) | 31/41 (75.61) | 24/41 (58.54) | 16/41 (39.02) | <0.001 |
| P# value | 0.012 | 0.001 | 0.240 | |
P∗ computed by Cochran's Q test.
P# computed by chi-square test or Fischer's Exact test.
Anti-spike antibody levels >15.0 arbitrary unit (AU)/mL were considered as seropositive while antibody level ≤15 AU/mL were considered as seronegative, as per the manufacturer's kit; V2- Second dose of vaccine.